Thin film transistor-liquid crystal display (TFT-LCD) is featured with small size, low power consumption, no radiation and the like, and thus dominates in the current flat-panel display market.
The TFT-LCD mainly comprises an array substrate and a color filter substrate bonded with each other. A plurality of pixel regions are provided on the array substrate in a matrix form. A thin film transistor (TFT) and a transparent pixel electrode are formed in each of the pixel regions. A color filter layer formed of a red (R) resin, a green (G) resin and a blue (B) resin and a black matrix are formed on the color filter substrate. The black matrix is provided to correspond to the thin film transistor to prevent light leakage.
Because of a misalignment between the array substrate and the color filter substrate during a bonding process, a width of the black matrix (BM) has to be increased to avoid light leakage caused by this misalignment. However, the aperture ratio of the pixel region is reduced in the case that the width of the black matrix is increased, and thus the display effect is degraded.
According to one technique, the color filter layer is formed on the array substrate to solve the problem mentioned above. In this case, the sequence of manufacturing the array substrate is as follows: TFT—passivation layer—passivation layer via hole—color filter layer—planarization layer made of resin (for planarizing surfaces of R, G and B resin)-transparent pixel electrode; or TFT—passivation layer—color filter layer—planarization layer made of resin—passivation layer via hole—transparent pixel electrode. Patterns of the color filter layer and the planarization layer made of resin are formed by the process of: forming patterns of the R, G and B resin through patterning processes, and forming the pattern of the planarization layer made of resin through a patterning process. Therefore, no matter which sequence is adopted, exposure processes have to be performed during forming the color filter layer and the planarization layer made of resin and the exposure amount is relatively large, which will result in a damage to the active layer (generally comprising a semiconductor layer and a doped semiconductor layer). Thus, the performance of the TFT and the display quality of the display device are reduced.
According to one technique, a light-shielding pattern is formed above the TFT through an additional patterning process to solve the problem mentioned above. However, the additional patterning process for forming the light-shielding pattern will cause an increase in manufacture cost of the array substrate. In addition, if the light-shielding pattern and other patterns (for example, the passivation layer via hole) are formed through a single patterning process with a multi-tone mask plate, the manufacture cost of the mask plate is increased and thus the manufacture cost of the array substrate is increased.